The present invention is directed to a capacitor discharge ignition circuit for an internal combustion engine and more particularly to a capacitor discharge ignition circuit in which all of the operative coils are wound as a single coil for disposition on one leg of a magnetic core.
Capacitor discharge ignition circuits are well known. Such circuits generally include a charging coil in which is generated the current utilized to charge a storage capacitor and a trigger coil utilized to generate the current necessary to effect operation of an electronic switch in the discharge circuit of the capacitor. The discharge circuit of the capacitor includes the primary winding of a high voltage transformer so that the operation of the electronic switch to discharge the capacitor through the primary winding provides ionization potential across the air gap of an ignition device such as a spark plug for an internal combustion engine.
It is known in such capacitor discharge ignition circuits that the charging coil and trigger coil may be wound on the same leg of a magnetic core whereby the timing of the charging and discharging of the ignition capacitor may be controlled. It is also known that a third coil may be utilized to insure the operation of the electronic switch during the normal charging operation of the storage capacitor to thereby shunt charging current away from the capacitor. Such coils are generally termed "shutoff" coils and are selectively switched into the ignition circuit when it is desired to terminate the operation of the internal combustion engine. The use of such shutoff coils is, for example, disclosed and claimed in the pending U.S. application Ser. No. 370,371 filed June 15, 1973, now U.S. Pat. No. 3,894,524 for "Capacitor Discharge Ignition System" and assigned to the assignee of the present invention.
The provision of charging, trigger and shutoff coils may require three separate coil manufacturing operations as well as separate assemblying steps, and it is an object of the present invention to provide a capacitor discharge ignition circuit in which all of the operative coils are wound as two single coils for disposition on the same leg of a magnetic core. One of the two coils may be tapped intermediate the ends thereof to separate the control functions and a substantial reduction in the size and expense of the circuit as well as minimization of the assemblying process is achieved thereby.
These and other objects of the present invention will become apparent to one skilled in the art to which the invention pertains from a perusal of the following detailed description when read in conjunction with the appended drawings.